At least for me, it is very common to design something that I think is pretty good only to redesign it later and then wish I hadn’t posted the earlier design. This is one of those. This folding scalpel pocket knife is very good IMHO. I made numerous design improvements that all resulted in simply a better knife.
Like the first version I released a month or so ago, this version is also a print-in-place design that requires no hardware, fasteners or adhesives. But what really makes this one so much better is…
- I made it slightly larger to accommodate the entire range of #4 handle scalpel blades. Including up to the 60A (or equivalent SwitchBack) blade. I have tested it with all the blades shown in the illustration below.
- This slightly larger design made it possible for me to strengthen the knife in many critical areas. And, as you know a few extra layers of print can really make a difference in strength and in this case, it has.
- The increased size and strength is complimented by an indexed spine mating with the blade side of the knife. This helps to reduce the side-to-side play in the knife.
- I created an offset of the radii in the pivot point. This is best understood by looking at the illustration below. I offset the internal radii so that in the print position there is a modest clearance of 0.5mm between the parts to ensure they do not fuse. But when the part is rotated 90 degrees the clearance is reduced to 0.3mm. This tightens the pivot at the fully open and closed positions. Creating a better feel and of course a better functionality.
Overall I feel this is a pretty good inexpensive and basically disposable/recyclable scalpel that I just might find myself using for a long time.
Printing
I have tried to make my main print settings visible on the Cura screenshot but in case they are difficult to read I have summarized them again here…
Material: I choose to use PETG for its durability and flexibility.
My Setup:
Nozzle = 0.4mm
My Settings:
Layer height = 0.2mm
Line width = 0.4mm
Wall count = 4 (1.6mm)
Infill = 40%
Ironing = ON
Support:
Designed to print without additional support. I have designed in one piece of support as shown in the accompanying illustration.
Print Orientation: As shown in the screenshot(s).
Assembly Notes
No assembly or post-print processing is required other than removing the one piece of support. Carefully break the blade end of the knife free by rotating back and forth on the pivot point. Install a scalpel blade.
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